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Rodenticide – what’s new with Rat Poison?

August 1st, 2014

In 2008 the U.S. Environmental Protection Agency (EPA) decided to prohibit the use of second-generation or long-acting anticoagulants in household rodenticides. Manufacturers were forced to be compliant with these regulations in 2011, and many now use bromethalin instead of anticoagulants in their products. Bromethalin is a neurotoxin that affects the part of the cell which helps turn food into energy (Mitochondria). This chemical also decreases ATP production, which is the chemical in cells that stores energy. This affects the brain, liver, and sodium and potassium pumps; which results in too much liquid accumulating in the central nervous system. The frightening reality is that with bromethalin, the new toxin of choice for rodenticide manufacturers, there is no known detection test and no antidote.

Ahna Brutlag, DVM, MS, of the American Board of Toxicology and assistant director of veterinary services for Pet Poison Helpline, says that the EPA made these changes to protect children and pets, but they have actually made treating rodenticide poisoning more difficult. The former standard poison (anticoagulants) has a very effective test to determine its presence and there is a known antidote. Anticoagulants also take 5-7 days to kill a person or pet, and therefore, there is much more time to save the life as opposed to bromethalin, where central nervous system swelling, abnormal behavior, ataxia, hyperesthesia, seizures, or coma may begin to take hold within just 24 hours. Once these neurological signs materialize, successful treatment becomes much less likely and more expensive. Toxicology experts purport that there has been a 65% increase in bromethalin exposure cases since the EPA banned second-generation anticoagulants.

Since there is no known antidote, it is imperative that Veterinarians are aware of the dangers of rodenticide poisonings and learn how to “decontaminate” bromethalin exposure; that is learn techniques to prevent the absorption of the toxic substance into the body. Ahna Brutlag has been traveling around the country educating Veterinarians on the switch to bromethalin; since so many Vets are unaware the change had occurred and were shocked to realize there is no antidote. Induced vomiting can be performed at home if exposure is discovered within ten to fifteen minutes of ingestion, but after that, it should take place in a Veterinary hospital, where the animal can be monitored for central nervous system failures and be given repeated doses of activated charcoal and IV fluids. If seizure or paralysis begin to take hold, unfortunately the prognosis is quite negative.

Because of the severe toxicity of bromethalin, some companies, like d-CON, have been outspoken objectors to the 2008 ruling, and had previously refused to comply with the new EPA standards, continuing to use a second-generation anticoagulant as its active ingredient. They cited the dangers of using a toxin with no known antidote as reason for non-compliance and have, along with support from the Pet Poison Hotline, been arguing that the EPA should revisit the 2008 regulation standards. Recently, d-CON and Poison Control came to an agreement to act in accordance with the ruling. This is because the EPA has introduced an acceptable alternative to bromethalin, a first-generation anticoagulant, called diphacinone. This change comes on the heels of a study that examined data collected concerning bromethalin exposure, and the discovery of diphacinone as a smarter choice. With diphacinone, the amount of time before the central nervous system collapses is significantly increased, which allows for more successful and less expensive treatment. Vitamin K, which nearly all Veterinary clinics have in stock, is an effective and inexpensive treatment and has a shorter recovery time to boot.

Few other rodenticide manufacturers seem inclined to follow d-CON back to anticoagulants at this time, but because d-CON is one of the largest manufacturers of rodenticides, their decision will have a significant impact on the industry. Veterinarians need to be aware of the different types of rodenticide in existence, know the warning signs and symptoms of each, and be familiar with varying treatments in order to be fully prepared.